Effects of residual oxygen on properties of cubic silicon carbide films

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We report the self-organized growth of 0D-, 1D- and 2D-nanoscale SiC structures (grains, whiskers, and flakes) by a hydrogen plasma sputtering technique in which a small amount of oxygen is added to the hydrogen feed gas. Selective growth of the different structure is controlled by the substrate temperature, whiskers below approximately 800℃, grains in the range 800-900℃, and flakes at higher temperature. In the case of the first, the additional O atoms bond to Si resulting in tetragonal SiO_2 microcrystals in the SiC films, which nucleate whisker growth electrostatically. When the substrate temperature is above 800℃ deposits of amorphous carbon break up the developing film into small grains. With further increase of temperature, the carbon deposits are increasingly graphitic due to preferential formation of sp^2 bonding due to the presence of oxygen, resulting in the growth of SiC flakes.